The invention relates to positive-action electric safety switches for breaking electric circuits.
In some known safety switches, a push-button or lever controlling an electric contact can be actuated in certain defined directions over given limited linear or angular paths. These switches are often clumsy to use, and may be dangerous since the contact has a limited movement and accidental movement of the control lever, for example, beyond a limiting position may damage the switch.
In other safety switches, breaking of an electric circuit is achieved by ripping away conducting wires, but these switches are imprecise and resetting can only be carried out by a repair technician, and short-circuits may be produced accidentally by contact of the loose wires with neighbouring metallic masses or bare conductors.
Another type of safety switch relies on the rupture of a rigid element such as a conducting rod or plate, but this involves the necessity of dismantling the switch and replacement of the ruptured element each time the switch is employed.
Finally, safety switches operating by inertia are known, for use in automobiles, wherein a spring-urged ball is held normally in a contactmaking position from which it can be displaced by inertia in the event of a collision. However, these switches are limited to use in vehicles, and are in particular not suitable for applications requiring manual actuation to break the circuit, nor when the switch has to be actuated in response to defined or random movements of a mechanical member.
An object of the invention is therefore to provide an electric safety switch suitable for manual or automatic actuation and which avoids the stated disadvantages.